Hello,
I am a native speaker of English so I do not fully know your position. But I self-taught some Greek and studied English Linguistics for 2 years, including how people learn English as a second language.
If I remember correctly, a native English speaker at university has about 25 000 'word families'. Think of a word family as a root word like 'eat', with relatives like 'eats, eating, eaten, ate' etc.
A non-native English speaker at an English university has about 5 000 word families - this is all that is really needed to be able to be considered fluent. This is because most language uses very similar words over and over. For example, the majority of words in a textbook are the same as a textbook in another subject, and special technical words are not used so often.
So, I would not worry too much about learning many new words but become very comfortable with the words you do know already, so maybe try and learn from different contexts.
I would watch TV shows or films of different types whose language you can understand, in order to learn the words and sentences better, by learning their use in different contexts.
Remember: it is almost always a sentence and not a word on its own that conveys meaning, and sentences depend on context.
Good luck.
P.S. If you only want to improve reading and handwriting, then my idea for films and TV shows is not very good!